To add further:
-*EACH* town building is down for 45 minutes. In other words, if you take down the first building at 12:00 and you take down the last one at 12:40 then in five minutes the first buildings you destroyed will come back up. We call this getting it "out of sync". This applies to the ack as well.
-If a troop is released within range of ANY existing auto-ack then it will simply disappear instantly. There is no need for the auto ack to actually shoot that troop down.
-At a few bases the base is very close to the town and the map room is within range of some of the base's auto ack as well, so in these few cases some of the base ack will need to be destroyed also.
-At bases that do not have a town (Vehicle Bases and most Ports) the only requirement is to get the auto-ack down at that base and to get 10 troops into the map room near the center of those bases, however as said before, it's a good idea to get the hangars and manned ack guns down as well so they can't manually kill the troops.
-While auto-ack is down for 45 minutes, an enemy can drop base supplies into the town and/or base to bring the auto-ack up sooner (I believe each box of supplies take 15 minutes off of that time). This includes the ack in the town! Even though it doesn't happen often, it will throw a wrench in the works when it does happen.
-Ground troop transports (M3, Jeep, LVT and that one with the rockets whose name escapes me right now) have to be completely stopped before letting the troops out, otherwise they will die. C47's have to be landed on the gear and completely stopped, -OR- flying at above 800 feet above ground level when troops are dropped, otherwise those troops will die too. (Yes I know it's possible to be moving slowly and for the troops to survive but we won't get into that right now)
-It is possible for the enemy to eject out of an airplane and land in the town in the parachute. Then they can kill troops with their pistol as they enter the maproom. If you've heard people yell "strafe the maproom" this is done as a preventative to kill any 'chutes' that may be hiding inside. 99.9% of the time this isn't a problem, but it's one of those "better safe than sorry" deals.